1. Field
The present disclosure relates generally to communication systems, and more particularly, to a method and apparatus for physical layer measurements in multicast broadcast multimedia service systems.
2. Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency divisional multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
Multimedia Broadcast Multicast Services (MBMS) is a point-to-multipoint interface specification for existing and upcoming 3GPP cellular networks. MBMS is designed to provide efficient delivery of broadcast and multicast services, both within a cell as well as within the core network. For broadcast transmission across multiple cells, it defines transmission via single-frequency network configurations. Target applications include mobile TV and radio broadcasting, as well as file delivery and emergency alerts.
LTE provides for enhanced Multimedia Broadcast Multicast Services (eMBMS) that offers transport features for sending similar content information to all users in a cell (broadcast) or to a given set of users (subscribers) in a cell (multicast). eMBMS is differentiated from IP-level broadcast or multicast, which does not offer sharing of resources on the radio access level. In eMBMS, it is possible to either use a single eNode-B or multiple eNode-Bs for transmission to multiple UEs. Multicast-Broadcast Single Frequency Network (MBSFN) is the definition for the latter.
MBSFN is a transmission mode that exploits LTE's OFDM radio interface to send multicast or broadcast data as a multi-cell transmission over a synchronized single-frequency network (SFN). The transmissions from the multiple cells are synchronized so that the transmissions arrive at the UE within the OFDM Cyclic Prefix (CP) so as to avoid Inter-Symbol Interference (ISI). In effect, this makes the MBSFN transmission appear to a UE as a transmission from a single large cell, dramatically increasing the Signal-to-Interference Ratio (SIR) due to the absence of inter-cell interference.
eMBMS provides certain quality parameters related to service level performance for MBSFN. However, these service level performance parameters are not directly related to eMBMS signal qualities. To improve performance of such data transfer operations as streaming and file transfer operations, having parameters directly related to eMBMS signal qualities available would be useful. For example, having physical layer measurements for eMBMS signals would be useful to determine network parameters.